Method of fabricating an angled ductwork fitting

ABSTRACT

Substantially scrapless methods for fabricating angled ductwork fittings. The methods include cutting a pre-determined pattern into a blank comprised of sheet metal material to separate the blank into two or more portions. Bending each of the portions of the blank so that each portion forms a rectangular section of ductwork pipe and joining the sections of ductwork pipe together to form an angled fitting. A transition fitting comprising a transition plate including a first panel and a second panel. The first panel is sized and shaped to be positioned in and to blank-off a gap between a first pipe and a second pipe. The second panel is positionable within the first pipe to direct fluid traveling through the first pipe into the second pipe.

FIELD OF THE INVENTION

The present invention is generally related to heating, ventilation and air conditioning (HVAC) ductwork systems, and more particularly to methods of fabricating angled rectangular ductwork fittings from a sheet of sheet metal material, or continuous sheet from a coil of sheet metal material in a substantially scrapless manner that greatly reduces waste or scrap.

BACKGROUND OF THE INVENTION

In general, ductwork is used in forced air heating and air conditioning ventilation systems to circulate air therethrough. Typically, the ductwork is fabricated from sheet metal, such as sheets of galvanized steel, carbon-steel, stainless steel and aluminum. One common type of ductwork is rectangular or box-shaped ductwork, which has four sides and a square or rectangular cross-section.

Rectangular ductwork can be fabricated using a variety of methods, and the method of fabrication typically depends on the size of the ductwork. For example, for ductwork used in residential or light commercial buildings, relatively small rectangular ductwork can be formed by what is sometimes referred to as the wrap-around method wherein a sheet of metal is bent along three bend lines to form the four-sided ductwork having a rectangular cross-section. In industrial or large-scale commercial use, which requires relatively large sections of ductwork, the ductwork can be formed from multiple pieces of sheet metal. For example, the ductwork can be formed by securing two L-shaped pieces of sheet metal together or by securing four pieces of sheet metal together wherein each sheet forms one of the four walls of the ductwork.

Installation of a ductwork system into a building requires both a series of straight runs and angled fittings. The angled fittings typically include elbows, offsets and transition, or change, fittings of varying degrees. Currently, such angled fittings for rectangular ductwork systems fabricated from sheet metal are created by methods which produce a substantial amount of waste. In such methods, each wall of the rectangular angled fitting is cut or stamped out of a flat sheet of sheet metal. The cut-out pieces or walls are then assembled together to form the angled fitting. For example, to fabricate a 90 degree elbow fitting, a top wall, bottom wall and two sidewalls are cut or stamped out of one or more sheets of metal. The top wall and the bottom wall are basically mirror images of each other and typically have arcuate portions that create the 90 degree bend in the fitting. The sidewalls are bent to conform to the top and bottom walls and then, the top wall, bottom wall and sidewalls are assembled together by a mechanical seam connection or welding. The only pieces of the original sheet metal material that are used to form the angled fitting are the cutout pieces, and the rest of the sheet metal material is waste or scrap.

Due to environmental concerns, there has been increasing pressure on builders to develop ways to reduce the amount of waste material created during a construction project. One environmental organization that provides guidelines and standards to builders is the U.S. Green Building Council (USGBC). The USGBC provides a rating system called Leadership in Energy and Environmental Design [LEED] Green Building Rating System. One of the categories that the LEEDs rating system takes into account is the amount of construction material waste created from a project.

Therefore, there remains a need for a fabrication process for creating angled rectangular ductwork fittings from sheet metal material that substantially reduces the amount of scrap or waste material and increases the overall efficiency of the fitting fabrication process.

SUMMARY OF INVENTION

The present invention generally related to substantially scrapless methods of fabricating angled rectangular metal ductwork fittings, such as elbows and offsets having various angles. The method generally comprises providing a generally flat piece of sheet metal material. For example, a piece of sheet metal that has been flattened after being unwound from a coil. The sheet metal material can be comprised of galvanized steel, carbon-steel, stainless steel, aluminum or any other suitable metal. A pre-determined pattern, which corresponds to a desired elbow or offset having a desired angle, is then cut through the sheet metal to divide the sheet metal into two or more sections, depending on the number of sections needed to construct the desired elbow or offset. Each of the sections is then bent to form a rectangular or boxed-shaped section of ductwork pipe having a mitered end. The sections of ductwork pipe are then orientated and the mitered ends of the ductwork pipe are secured together.

Another aspect of the present invention generally relates to a method of fabricating an angled fitting for a rectangular ductwork system comprising cutting a pre-determined continuous circumferential pattern through the walls of a rectangular ductwork pipe to separate the ductwork pipe into two or more sections of ductwork pipe. Orienting the sections of ductwork pipe into a desired orientation and mechanically joining the sections of ductwork pipe together to form an angled ductwork fitting.

Yet another aspect of the present invention is generally related to a blank for fabricating a rectangular angled ductwork fitting that comprises a substantially flat sheet of sheet metal material having a top edge and a bottom edge and at least one indicator forming a predetermined cutting patterning substantially extending from the top edge to the bottom edge. The blank can be cut along the indicator to form two or more portions of the blank that can be bent into rectangular sections of ductwork pipe. The rectangular sections of pipe can be assembled to form an angled ductwork fitting.

A further aspect of the present invention is generally related to a ductwork pipe for fabricating an angled ductwork fitting that comprises a rectangular metal pipe including a top wall, a bottom wall and opposed sidewalls. The pipe also includes at least one indicator forming a pre-determined cutting pattern extending circumferentially around the pipe. The pipe can be cut along the cutting pattern to form segments of ductwork pipe that can be connected together to form an angled ductwork fitting.

Another aspect of the present invention is generally related to a transition fitting for a ductwork system that comprises a transition plate that can be installed in a transition fitting connecting a first pipe having a width and a second pipe having a width that is less than the width of the first pipe. The transition plate includes a first panel and a second panel wherein the first panel is sized and shaped to be positioned in and to blank-off a gap between the first pipe and the second pipe. The second panel is positioned within the first pipe so as to direct fluid traveling through the first pipe into the second pipe.

Other aspects, objects and advantages of the present invention will be understood from the following description according to the preferred embodiments of the present invention, specifically including stated and unstated combinations of the various features which are described herein, relevant information concerning which is shown in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In describing the preferred embodiments of the present invention, reference will be made to the accompanying drawings, wherein:

FIG. 1 is a top view of a sheet metal blank that can be used in the fabrication process of the present invention;

FIG. 2 is a top view of the sheet metal blank of FIG. 1 including a cutting pattern represented by a solid line and bend lines represented by dashed lines;

FIG. 3 is a perspective view of two segments of rectangular ductwork pipe that can be formed by cutting and bending the blank of FIG. 2;

FIG. 4 is a cross-sectional view of one of the segments of ductwork pipe of FIG. 3, showing one method of securing the ends of the blank to form the rectangular ductwork pipe;

FIG. 5 is a perspective view of an angled ductwork fitting that can be fabricated from the sections of ductwork pipe of FIG. 3;

FIG. 6 is a cross-sectional view of the angled fitting of FIG. 5 shown with an s-slip to assist in securing the first and second sections of ductwork pipe together;

FIG. 7 is a top view of another embodiment of a sheet metal blank of the present invention;

FIG. 8 is a perspective view of one embodiment of a ductwork pipe of the present invention;

FIG. 9 is a top view of another embodiment of a sheet metal blank of the present invention shown with cutting patterns represented by solid lines and bend lines represented by dashed lines;

FIG. 10 is a perspective view of the three sections of ductwork pipe that can be fabricated from the blank of FIG. 9;

FIG. 11 is a perspective view of one embodiment of an angled fitting that can be fabricated from the sections of ductwork pipe of FIG. 10;

FIG. 12 is a top view of another embodiment of a sheet metal blank of the present invention shown with cutting patterns represented by solid lines and bend lines represented by dashed lines;

FIG. 13 is a perspective view of the three sections of ductwork pipe that can be fabricated from the blank of FIG. 12;

FIG. 14 is a perspective view of an angled fitting that can be fabricated from the sections of ductwork pipe of FIG. 13;

FIG. 15 is a perspective view of a first ductwork pipe adjoined to a second smaller ductwork pipe;

FIG. 16 is a top view of one embodiment of a transition plate of the present invention; and

FIG. 17 is a perspective view of a transition fitting of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriate manner.

The methods of fabricating angled metal ductwork fittings and the related devices described herein can be used to substantially reduce or eliminate the amount of scrap metal material that is typically created by conventional methods of forming such fittings. Thus, it will be apparent from the following description that in the methods described herein all or substantially all of the sheet metal material is utilized in the creation of an angled fitting. Such reduction in waste material will aid builders in building structures that conform to the LEED rating system.

As used herein, the term “angled fitting” or “angled ductwork fitting” is meant to include pieces of ductwork, such as elbows, offsets and transition fittings of varying degrees, that when fitted together, provide a non-linear path through the assembled ductwork.

FIG. 1 generally illustrates one embodiment of a blank 10 of sheet metal material that can be used in the methods of the present invention to fabricate an angled ductwork fitting. The blank 10 is preferably a substantially flat rectangular sheet of metal having a top marginal edge 12, a bottom marginal edge 14 and first and second opposed side marginal edges 16, 18. The blank 10 of sheet metal can be comprised of galvanized steel, carbon steel, stainless steel, aluminum or any other metal or metal alloy that is suitable for ductwork.

The blank 10 can vary in size depending on the desired size of the finished angled ductwork fitting. For example, for small ductwork sizes, typically used in residential and light commercial ductwork systems, the blank can have a length up to 70-inches long for a one-piece, three-bend, wrap-up ductwork configuration. For larger industrial and commercial ductwork systems, the blank length is up to 120-inches long for a two-piece configuration of ductwork comprised of two “L”-shaped sections of formed sheet metal. For even larger ductwork sizes where the sum of two adjacent sides exceeds 120-inches, the blank can be comprised of four or more panels of sheet metal material that are used to form the ductwork. This multi-panel fabrication process can be used to fabricate ductwork of unlimited sizes. Thus, it should be understood that the blank 10 can be one continuous piece of sheet metal material or the blank 10 can be multiple pieces of sheet metal material that are adjoined together before or during the fabrication of the angled ductwork fitting.

FIG. 2 through FIG. 6 generally illustrate one method of the present invention for fabricating a two-sectioned elbow fitting. In general, the method comprises cutting and bending the blank 10 to form two or more sections of ductwork pipe that are then assembled together to form the angled fitting. Referring to FIG. 2, the blank 10 is first divided into four sections 20, 22, 24 and 26. The division of the blank 10 into such sections is represented in FIG. 2 by dashed lines A, B and C. In one embodiment of the method, the dashed lines A, B and C can be physical indicia located on the blank 10 that indicates where the blank is to be bent. As will be explained below, each of the sections 20, 22, 24 and 26 corresponds to and forms one of the walls of the rectangular ductwork pipes shown in FIG. 3.

A cutting pattern D is cut through the blank 10 to divide the blank into a first portion 30 and a second portion 32. For example, the blank is cut continuously along cutting pattern D from the top marginal edge 12 to the bottom marginal edge 14 to divide the blank. In the illustrated embodiment, the cutting pattern D includes a perpendicular cut line 34 through section 20 extending from the top marginal edge 12 to the dashed line A. An angled cut line 36 through section 22 extends from the end of cut line 34 to the dashed lined B. The angled cut line 36 extends at an angle E relative to cut line 34. The value of angle E of cut line 36 can vary and depends on the desired angle of the finished joint fitting. For example, in the illustrated embodiment, angle E is 22.5 degrees, which will result in a finished joint fitting having an angle of 45 degrees. In general, angle E of cut line 36 will have a value of about half of the desired value of the angle of the joint fitting. For instance, if the desired angle of the finished joint fitting is 90 degrees, angle E of cut line 36 will be 45 degrees, and if the desired angle of the finished joint fitting is 60 degrees, angle E of cut line 36 will be about 30 degrees.

The cutting pattern D also includes cut line 38 through section 24 extending from cut line 36 to dashed line C. The cut 38 is generally parallel to cut line 34 and extends perpendicular to dashed lines B and C. A second angled cut line 40 through section 26 extends from cut line 38 to bottom marginal edge 14. Angled cut line 40 is made at an angle F relative to cut line 38. The value of angle F is substantially equal to the value of angle E of cut line 36. The blank can be cut with the use of any suitable type of cutting instrument, such as a plasma cutter, laser cutter, high pressure water cutter or circular saw.

After the blank 10 has been cut into a first portion 30 and a second portion 32, each portion 30, 32 is bent along dashed lines A, B and C to form a first section of rectangular ductwork pipe 42 and a second section of rectangular ductwork pipe 44, shown in FIG. 3. The first section of rectangular ductwork pipe 42, which is formed from portion 30 of blank 10, includes a top wall 20 a, a bottom wall 24 a and opposed sidewalls 22 a, 26 a that respectively correspond with sections 20, 22, 24 and 26 of blank 10. The section of pipe 42 includes a mitered end portion 45 and a planar end portion 47.

Additionally, the first section of ductwork pipe 42 includes corners 46, 48, 50 and 52. Corners 46, 48 and 50 correspond to the locations of bending of the blank 10 represented by dashed lines A, B and C, respectively. Corner 52 is formed by the joining of the top marginal edge 12 and the bottom marginal edge 14. In one embodiment, as illustrated in FIG. 4, the top marginal edge 12 and the bottom marginal edge 14 can be mechanically joined together, such as by what is sometimes referred to as a Pittsburg lock 54. Alternatively, the top marginal edge 12 and bottom marginal edge 14 can be joined together by any other suitable means, mechanical or otherwise, such as by welding.

The second section of rectangular ductwork pipe 44 is formed by bending portion 32 of blank 10 along bend lines A, B and C. The pipe 44 includes a mitered end 55 and a planar end 57. The second portion of ductwork pipe 44 also includes a top wall 20 b, a bottom wall 24 b and opposed sidewalls 26 b, 22 b that correspond with sections 20, 24, 26 and 22 of blank 10, respectively. Furthermore, the locations of dashed lines A, B and C of blank 10 form corners 56, 58 and 60 respectfully, and corner 62 is formed by joining top marginal edge 12 and bottom marginal edge 14 using any of the methods described above.

After the two sections of ductwork pipe 42, 44 have been formed, they are oriented and assembled together to form an angled ductwork fitting 66 (FIG. 5). For instance, the second section of ductwork pipe 44 is rotated 180 degrees along the longitudinal axis X from the position illustrated in FIG. 3. The mitered end 55 of the second pipe 44 is inserted into the mitered end 45 of the first pipe 42 so that the mitered end 55 of the second pipe 44 overlaps the mitered end 45 of the first pipe 42. To assist in inserting the mitered end 55 of the second pipe 44 into the mitered end 45 of the first pipe 42, the ends of corners 64 of the mitered end portion 55 of the second pipe can be removed or notched out. The notched out corners 64 allow the walls of the second section of pipe 44 to slightly flex inward so that the mitered end 55 of the pipe 44 fits within the mitered end 45 of the first pipe 42. After the mitered end 55 of the second pipe is positioned inside the mitered end 45 of the first pipe 42, fasteners such as sheet metal screws can be used to fasten together the overlapped portions of the mitered ends 45, 55 of the first and second section of ductwork pipe 42, 44. The value of the angle G of the ductwork fitting 66 is about twice the value of angle E.

The first and second sections of ductwork pipe 42, 44 can also be assembled using other methods. For example, referring to FIG. 6, s-slip connectors 67 can be used to connect the first and second sections of pipe 42, 44. Alternatively, the mitered ends 45, 55 can be butted up against each other and self adhesive strips of galvanized metal material or heavy metal foil tape can be used to join the first and second sections of pipe 42, 44 together or a double s-cleat having a slight angle could be used. Additionally, the first and second sections of pipe 42, 44 can be welded together or can be adjoined together by a flange type connection.

FIG. 7 illustrates another embodiment of a sheet metal blank 69 that can be used in the methods of the present invention to fabricate an angled ductwork fitting. The blank 69 is generally similar to blank 10. However, in this embodiment, the blank 69 includes a physical indicator 68 that extends from the top marginal edge 70 to the bottom marginal edge 72 and separates the blank 69 into a first portion 74 and a second portion 76. The physical indicator 68 can be used as a guide to cut the blank 66 and divide it into the first and second portions 74 and 76. Additionally, the physical indicator 68 can be physical indicia or marking, such as a solid or dashed pattern, printed on or etched into the blank or can be an intermittent cut or perforation through the sheet metal.

In the embodiment shown in FIG. 7, the pattern of the indicator 68 is substantially similar to the cutting pattern D shown in FIG. 2. It will also be understood that similar to the cutting pattern of FIG. 2, angles H and I of the indicator 68 can vary depending on the desired angle of the finished joint fitting. Furthermore, the shape and design of the pattern of the indicator 68 is not limited to that shown in FIG. 7 and can comprise any number of the shapes and designs, such as the cutting patterns shown in FIGS. 9 and 12 and discussed in more detail below.

Blanks having physical indicators can be employed in a variety of different fashions to fabricate an angled fitting. For example, in one method, a ductwork installer could determine the type of angled ductwork fitting that is needed during the installation of a ductwork system. The installer can then choose a blank that has a physical indicator that when cut will produce sections of ductwork pipe that could be assembled to create the desired fitting. After the installer chooses the desired blank, the installer can cut along the physical indicator to divide the blank into portions that can be bent into rectangular sections of pipe similar to those shown in FIG. 3. For example, in the blank 69 shown in FIG. 7, the installer would cut along physical indicator 68 to separate the first portion 74 from the second portion 76. After the blank 69 is divided, the portions 74, 76 are bent to form rectangular sections of ductwork pipe similar to those shown in FIG. 3. The rectangular pipes are then assembled in a generally similar fashion as described above to form the angled ductwork fitting shown in FIG. 5.

In an alternative method, the blank 69 is first bent to form a ductwork pipe, such as the ductwork pipe 78 shown in FIG. 8. After the ductwork pipe 78 is formed, the ductwork pipe is cut along the physical indicator 68 to divide the ductwork pipe into a first section and a second section, similar to those shown in FIG. 3. The first and second sections of ductwork pipe are then assembled in a generally similar fashion as described above to form the finished angled ductwork fitting shown in FIG. 5. It will be understood that the blank having the desired pattern could be bent into the ductwork pipe in the factory prior to being obtained by the installer. In such a case, the installer would determine the type of angled ductwork fitting needed and then choose the appropriate ductwork pipe having a physical indicator of a desired pattern. Furthermore, it should also be understood that a blank could be bent to form the pipe shown in FIG. 8, and then the physical indicator could be placed on the pipe.

FIG. 9 illustrates another embodiment of a blank 80 that can be used in the methods of the present invention to fabricate an angled ductwork fitting. The blank 80 can be divided into four sections 82, 84, 86 and 88 as indicated by lines J, K and L. A first pattern M and a second pattern N can be cut through the blank 80 to separate the blank into a first portion 90, a second portion 92 and third portion 94.

The first pattern M includes a cut line 96 through section 82 extending from the top marginal edge 98 to dashed line J. An angled cut line 100 through section 84 extends from the cut line 96 to dashed bend line K. The angled cut line 100 extends at an angle O relative to cut line 96. The value of angle O can vary, depending on the desired angle of the finished joint fitting, and is generally about one fourth the value of the angle of the desired joint fitting. In the illustrated embodiment, the angle O is about 22.5 degrees, which will result in an angled fitting of about 90 degrees (FIG. 11).

The cutting pattern M also includes a cut line 102 through section 86 extending from cut line 100 to dashed line L. The cut line 102 is generally parallel to cut line 96 and perpendicular to dashed lines K and L. A second angled cut line 104 through section 88 extends from cut line 102 to marginal bottom edge 106. The second angled cut line 104 extends at an angle P relative to cut line 102 wherein angle P is substantially equal to angle O.

The second cutting pattern N is preferably a mirror image of cutting pattern M and includes a cut line 108 through section 82, an angled cut line 110 through section 84 at angle Q from cut line 108, a cut line 112 through section 86 that is parallel to cut line 108 and an angled cut line 114 through section 88 at an angle R from cut line 112. The values of angles Q and R are preferably substantially the same as the value of angle O. However, the values of angles Q and R could also be a different value from the value of O.

After the blank 80 has been cut and divided into the three portions, the first portion 90 can then be bent along dashed lines J, K and L to form a first section of rectangular ductwork pipe 116, as illustrate in FIG. 10. The ductwork pipe 116 is comprised of a top wall 82 a, a bottom wall 86 a, and a pair of opposed sidewalls 84 a, 88 a that respectively correspond with sections 82, 86, 84 and 88 of blank 80. The section of pipe 116 also includes a mitered end portion 118 and a planar end portion 120.

The second portion 92 of the blank 80 is bent along dashed lines J, K and L to form a second section of rectangular ductwork pipe 122. The ductwork pipe 122 is comprised of a top wall 82 b, a bottom wall 86 b and a pair of opposed sidewalls 84 b, 88 b that respectfully correspond with sections 82, 86, 84 and 88 of blank 80. The second section of ductwork pipe 122 also includes a first mitered end portion 124 and a second mitered end portion 126.

The third portion 94 of the blank 80 is bent along dashed lines J, K and L to form a third section of ductwork pipe 128. The ductwork pipe 128 is comprised of a top wall 82 c, a bottom wall 86 c and a pair of opposed sidewalls 84 c, 88 c that correspond with sections 82, 86, 84 and 88 of blank 80. The third section of ductwork pipe 128 also includes a mitered end portion 130 and a planar end portion 132.

After the three sections of ductwork pipe 116, 122 and 128 have been formed, the second piece of ductwork pipe 122 is rotated 180 degrees about the longitudinal axis X₁ and the sections of ductwork are assembled together to form the ductwork fitting 134 shown in FIG. 11. To assemble the ductwork fitting 134, the mitered end portion 124 of pipe 122 is connected to the mitered end portion 118 of pipe 116 and the mitered end portion 126 of pipe 122 is connected to mitered end portion 130 of pipe 128. The mitered end portions of the pipe can be connected by any of the methods of connection described above. As mentioned above, the value of angle 135 of the elbow joint fitting is about four times the value of angle O. Accordingly, in the embodiment illustrated in FIG. 11, the angle 135 of the elbow joint fitting is 90 degrees.

FIG. 12 illustrates another embodiment of a blank 136 that can be used in the methods of the present invention to fabricate an angled ductwork fitting. The blank 136 can be divided into four sections 138, 140, 142 and 144 as indicated by dashed lines S, T and U. A first pattern V and a second pattern W can be cut through the blank 136 to separate the blank into a first portion 146, a second portion 148 and third portion 150.

The first pattern V includes a cut line 152 through section 138 extending from the top marginal edge 154 to dashed line S. An angled cut line 156 through section 140 extends from the cut line 152 to dashed line T. The angled cut line 156 extends at an angle Y relative to cut line 152. The value of angle Y can vary, depending on the desired angle of the finished joint fitting, and is generally about half the value of the angle of the desired joint fitting. In the illustrated embodiment, the angle Y is about 22.5 degrees, which will result in an angled off set fitting of about 45 degrees (FIG. 14).

The cutting pattern V also includes a cut line 158 through section 142 extending from cut line 156 to dashed line U. The cut line 142 is generally parallel to cut line 152 and perpendicular to dashed lines T and U. A second angled cut line 160 through section 144 extends from cut line 158 to marginal bottom edge 162. The second angled cut line 160 extends at an angle Y₁ relative to cut line 158 wherein the value of angle Y₁ is substantially equal the value of angle Y.

The second cutting pattern W preferably has substantially the same shape of cutting pattern V and includes a cut line 164 through section 138, an angled cut line 166 through section 140 at an angle Z from cut line 164, a cut line 168 through section 142 that is parallel to cut line 164 and an angled cut line 170 through section 144 at an angle Z₁ from cut line 168. The values of angles Z and Z₁ are preferably substantially the same as the value of angle Y. However, the values of angles Z and Z₁ could also be of a different value than Y.

After the blank 136 has been cut and divided into the three portions, the first portion 146 can then be bent along dashed lines S, T and U to form a first section of rectangular ductwork pipe 172, as illustrated in FIG. 13. The ductwork pipe 172 is comprised of a top wall 138 a, a bottom wall 142 a, and a pair of opposed sidewalls 140 a, 144 a that respectively correspond with sections 138, 142, 140 and 144 of blank 136. The section of pipe 172 also includes a mitered end portion 174 and a planar end portion 176.

The second portion 148 of the blank 136 is bent along bend dashed lines S, T and U to form a second section of rectangular ductwork pipe 178. The ductwork pipe 178 is comprised of a top wall 138 b, a bottom wall 142 b and a pair of opposed sidewalls 140 b, 144 b that respectfully correspond with sections 138, 142, 140 and 144 of blank 136. The second section of ductwork pipe 178 also includes a first mitered end portion 180 and a second mitered end portion 182.

The third portion 150 of the blank 136 is bent along dashed lines S, T and U to form a third section of rectangular ductwork pipe 184. The ductwork pipe 184 is comprised of a top wall 138 c, a bottom wall 142 c and a pair of opposed sidewalls 140 c, 144 c that correspond with sections 138, 142, 140 and 144 of blank 136. The third section of ductwork pipe 184 also includes a mitered end portion 186 and a planar end portion 188.

After the three sections of ductwork pipe 172, 178 and 184 have been formed, the second piece of ductwork pipe 178 is rotated 180 degrees about the longitudinal axis X₂ and the sections of ductwork are assembled together to form the offset ductwork fitting 190 shown in FIG. 14. To assemble the ductwork fitting 190, the mitered end portion 180 of pipe 178 is connected to the mitered end portion 174 of pipe 172 and the mitered end portion 182 of pipe 178 is connected to mitered end portion 186 of pipe 184. The mitered end portions of the each pipe can be connected by any of the methods of connection described above. As mentioned above, the value of angle 192 of the offset joint fitting is twice the value of angle Y. Accordingly, in the embodiment illustrated in FIG. 14, the angle 192 of the offset joint fitting is 45 degrees.

Another aspect of the present invention relates to transition fittings and methods of using the same for connecting different sized pipe of ductwork together. In conventional methods of joining pipes of different widths together, transition fitting having complex angles are used to join the pipes together. Typically, these conventional transition fittings are fabricated from cutting out individual pieces from sheet metal material and assembling the pieces together to form the fitting.

As will be appreciated from the following description, the transition fittings and methods described herein eliminate the need for a complex transition fitting, reduce the amount of material needed for the transition fitting and reduce the amount of scrap or waste material.

In one embodiment of a method of the present invention, referring to FIG. 15, a first rectangular ductwork pipe 200, having a width 202, is joined to a second rectangular ductwork pipe 204, having width 206 that is smaller than width 202 of the first ductwork pipe 200. The first and second ductwork pipes 200, 204 are connected by joining an end portion 208 of the first ductwork pipe 200 to an end portion 210 of the second ductwork pipe 204. The end portions 208, 210 of the ductwork pipes can be adjoined by any suitable type of connection, such as a drive slip connection, an s-slip connection, a flanged connection or welding. The first and second ductwork pipes 200, 204 are connected so that wall 212 of the first ductwork pipe 200 and wall 214 of the second ductwork pipe 204 are generally aligned and a gap or opening 216 exists between the edge 218 of the end portion 208 of the first ductwork pipe 200 and the edge 220 of end portion 210 of the second ductwork pipe 204. Additionally, the first and second pipes are preferably substantially the same depth so that the top and bottom walls of the pipes generally align.

The gap 216 between the edge 218 of the first ductwork pipe 200 and the edge 220 of the second ductwork pipe 204 can be blanked or closed off by a transition plate 222 (FIG. 16). The transition plate 222 is preferably comprised of a sheet metal material which has been cut out or stamped out of a sheet of sheet metal material. The transition plate 222 can include a first or blanking panel 224 and a second or fluid directing panel 226. The first panel 224 is substantially the same size and shape as gap 216. In the illustrated embodiment, the first panel 224 is a rectangular panel defined by edges 228, 230, 232 and 234. The first panel 226 includes a first securing flap 236 extending from edge 228, a second securing flap 238 extending from edge 230 and a third securing flap 240 extending from edge 232. The transition plate 222 can be bent along edges 228, 230, 232 so that the securing flaps 236, 238, 240 extend at an angle from panel 224.

In the illustrated embodiment, second panel 226 also has a generally rectangular shape defined by edges 234, 242, 246 and 248. The second panel 226 also can have shapes other than rectangular. The transition plate 222 may be bent along edge 234 to create an angle between the first panel 224 and the second panel 226. The second panel 226 also includes a securing flap 250 extending from the edge 244 of the second panel. The securing flap 250 can be bent to extend from the second panel 226 at a desired angle and is employed to secure the transition plate to the first ductwork pipe.

Referring to FIG. 17, the transition plate 222 is bent along edge 234 so as to create an angle between the first panel 224 and the second panel 226. The plate 222 is also bent along edges 228, 230 and 232 so that the securing flaps 236, 238, 240 extend at right angles to the first panel 224. The transition plate 222 is then positioned within the first ductwork pipe 200 so that the first plate 224 is located within gap 216, thereby blanking or closing off gap 216, and the second plate 226 is located within the interior of the first pipe 200. The first securing flap 236 of the first panel 224 is then secured to the top wall 252 of the pipe 200, the second securing flap 238 is secured to the sidewall 254 of pipe 200 and the third securing flap 240 is secured to the bottom wall 256 of pipe 200. Furthermore, the securing flap 256 of the second plate 226 is bent back and secured to sidewall 254 of the pipe 200. The securing flaps can be secured to the ductwork by the use of sheet metal screws.

When the transition plate 222 is installed, the second panel 226 is at an angle relative to the first and second ductwork pipes 200, 204 and blocks off the dead space 258 defined by the wall 254, the first panel 224 and the second panel 226. As fluid flows through the first pipe 200 toward the second pipe 206, the second panel 226 prevents fluid from flowing into the dead space 258 and directs fluid into the second pipe 204.

It will be understood that the embodiments of the present invention which have been described are illustrative of some of the applications of the principles of the present invention. Numerous modifications may be made by those skilled in the art without departing from the true spirit and scope of the invention, including those combinations of features that are individually disclosed or claimed herein. 

1. A method of fabricating an angled fitting for a rectangular ductwork system, comprising: providing a substantially flat blank of sheet metal material having a top edge and a bottom edge; cutting a pre-determined pattern in the blank from the top edge to the bottom edge to separate the blank into two or more portions; bending each of the portions of the blank so that each portion forms a discrete section of rectangular ductwork pipe; and joining the sections of rectangular ductwork pipe together to form an angled ductwork fitting.
 2. The method of claim 1 in which the cutting a pre-determined pattern in the blank comprises separating the blank into two portions.
 3. The method of claim 1 in which the cutting a pre-determined pattern in the blank comprises separating the blank into three portions.
 4. The method of claim 1 in which the angled ductwork fitting formed by joining the sections of rectangular ductwork pipe is an elbow fitting.
 5. The method of claim 1 in which the angled ductwork fitting formed by joining the sections of rectangular ductwork pipe is an offset fitting.
 6. A method of fabricating an angled fitting for a rectangular ductwork system, comprising: providing a rectangular metal ductwork pipe having a top wall, a bottom wall and first and second opposed sidewalls; cutting a pre-determined continuous circumferential pattern through the top wall, bottom wall and first and second opposed sidewalls to separate the pipe into two or more sections of ductwork pipe; orienting the sections of ductwork pipe into a desired orientation; and mechanically joining the sections of ductwork pipe together to form an angled ductwork fitting.
 7. The method of claim 6 in which the cutting a pre-determined continuous circumferential pattern in the ductwork pipe comprises separating the ductwork pipe into two sections.
 8. The method of claim 6 in which the cutting a pre-determined continuous circumferential pattern in the ductwork pipe comprises separating the ductwork pipe into three sections.
 9. The method of claim 6 in which the angled ductwork fitting formed by joining the sections of ductwork pipe is an elbow fitting.
 10. The method of claim 6 in which the angled ductwork fitting formed by joining the sections of ductwork pipe is an offset fitting.
 11. A blank for fabricating a rectangular angled ductwork fitting, comprising: a substantially flat sheet of sheet metal material having a top edge and a bottom edge; and at least one indicator forming a predetermined cutting patterning substantially extending from the top edge to the bottom edge, said blank adapted to being cut along said indicator to form two or more portions of the blank, each of said portions being adapted to being bent into a rectangular section of ductwork pipe, wherein the rectangular sections of pipe can be assembled to form an angled ductwork fitting.
 12. The blank of claim 11 in which the flat sheet of metal comprises galvanized steel.
 13. The blank of claim 11 in which the indicator comprises perforations in the blank.
 14. The blank of claim 11 furthering including a second indicator forming a cutting pattern extending from the top edge to the bottom edge of the blank.
 15. The blank of claim 11 in which the flat sheet of metal material comprises a plurality of metal pieces.
 16. A ductwork pipe for fabricating an angled ductwork fitting, comprising: a rectangular metal pipe including a top wall, a bottom wall and opposed sidewalls, and at least one indicator forming a pre-determined cutting pattern extending circumferentially around the pipe, said pipe adapted to being cut along the cutting pattern to form segments of ductwork pipe that connect together to form the angled ductwork fitting.
 17. The ductwork pipe of claim 16 in which the indicator comprises perforations through the ductwork pipe.
 18. A transition fitting for a ductwork system, comprising: a transition plate adapted for being installed in a transition fitting connecting a first pipe having a width and a second pipe having a width that is less than the width of the first pipe, said transition plate comprising a first panel and a second panel, said first panel sized and shaped to be positioned in and to blank-off a gap between the first pipe and the second pipe, said second panel positioned within the first pipe so as to direct fluid traveling through the first pipe into the second pipe.
 19. The transition fitting of claim 18 in which the first panel includes at least on securing flap extending from an edge of the first panel, said securing flap adapted to assist in securing the transition plate to the first pipe.
 20. The transition fitting of claim 18 in which the second panel includes at least one securing flap extending form an edge of the first panel, said securing flap adapted to assist in securing the transition plate to the first pipe. 